Soil pulverizing device

ABSTRACT

A device for use in compaction testing wherein a soil sample is provided in a mold and is thereafter pulverized to a fine state. The device of the invention comprises a base for supporting the mold and a pulverizing blade. The blade is supported adjacent a mold mounted on the base, and drive means are associated with the blade for rotating the blade relative to the mold while simultaneously moving the blade inwardly for engaging material in the mold. The blade defines a cutting edge including a serrated portion and a scraping and auger portion for achieving the soil pulverizing action while simultaneously removing at least some of the pulverized material from the mold.

United States Patent 1191 Bowles Feb. 11, 1975 SOIL PULVERIZING DEVICE Primary Examiner-Granville Y. Custer, Jr. [76] Inventor' ggf ffifi g g l H] wood Assistant Examiner-Howard N. Goldberg Attorney, Agent, or Firm-McDougall, Hersh and [22] Filed: Jan. 8, 1973 Scott [21] Appl. N0.: 321,692

I ['57] ABSTRACT [52] U.S. Cl 241/278 R, 241/282], 241/297,

408/223 A device for use 1n compact1on testlng wherem a SOll [51] Int. Cl. B02c 18/14 Sample is Provided in a mold and is thereafter, pulver- [58] Field Of Search 241/277, 278 R, 282.1, ized to a fine State- The device of the invention 24l/282.2, 292.1, 296, 297, 101.4, 168, prises a base for supporting the mold and a pulverizing 1691; 403/223 blade. The blade is supported adjacent a mold mounted on the base, and drive means are associated [56] References Cited with the blade for rotating the blade relative to the UNITED STATES PATENTS mold while simultaneously moving the blade inwardly for engaging material in the mold. The blade defines a lgggg z 335 cutting edge including a serrated portion and a scrap- ;,5Ol,687 3/1950 Mayer D. 241/ ingand auger portion for achieving the soil pulverizing 2:906:3l0 9/1959 semen :III.II:.:I...III.I: 241/296 x whlle smulaneously remwmg least some of 2,953,179 9/1960 Friess 24l/282.2 x the pulverized material from the mold- FORElGN PATENTS OR APPLICATIONS 5 Chin's, 7 Drawing Figures 398.289 8/1922 Germany 241/277 llllllll as 8 se arr: 7-91:-

lllfl lli ii lll 24 PATENIED FEB] 1 I975 SHEET 1 OF 2 l SOIL PULVERIZING DEVICE Thisinventionrelates to a soil pulverizing device. in a particular, the invention is directed to a construction utilized in connection with compaction testing operations.

in the construction industry, it is necessary to provide means for testing the soil conditions at the site ofa proposed or existing building or other structu re. Where cut and fill operations are necessary, the testing program includes obtaining samples of soil from the site to determine the required density of the in-place fill material and other significant properties.

The density of the in-place fill is generally specified on the basis of a laboratory compaction test on soil obtained from the construction site. In such testing, soil is compacted in a mold using a specified compaction energy, and generally on soil pulverized to pass a No.

. 4 sieve. The moisture content of the soil is determined,

In practice, the compaction testing has involved various methods for pulverizing the soil after each density determination is made. Compacted samples have been reduced to a fine state (or minus No. 4 sieve size) by scraping with spatulas, scraping with wire frames, using wood rasps or other similar means. it has been found that these techniques are quite inefficient from the standpoint of the time necessary for obtaining the pulverized soil. In addition, it has been found to be extremely difficult to obtain acceptable material size in the pulverized soil when these techniques are used. If the pulverized soil is coarser for a compacted specimen, the effect of moisture addition on density may vary when compared with a different compacted specimen using soil which has been broken down to a finer state.

The standard sample pulverizing techniques are also made more difficult when the compaction effort is increased from the standard test procedure which uses approximately 12,400 foot pounds per cubic foot of energy. ln the modified compaction test, the compaction energy input exceeds 56,000 foot pounds per cubic foot, and the compacted specimens can be as hard as low class bricks. Accordingly, a considerable amount of effort is required on the part of a technician to reduce these specimens to the desired fine state which must be sufficient to pass a No. 4 sieve in accordance with ASTM and AASHO standards.

it is a general objective of this invention to provide an improved soil pulverizing device whereby compacted soil specimens can be reduced to essentially the minus No. 4 sieve size in an efficient and consistent manner.

It is a more specific objective of this invention to provide a unique soil pulverizing device which is mechanically operated for reducing the compacted soil to a minus No. 4 sieve state.

lt is a still further objective of this invention to provide a device which accomplishes the foregoing objectives while substantially reducing the time and effort required for obtaining pulverized soil and while enabling the production of consistent pulverized material during the successive stages of a compaction test operation.

These and other objects of this invention will appear hereinafter and for purposes of illustration, but not of limitation, specific embodiments of the invention are shown in the accompanying drawings in which:

H6. 1 is a perspective view of a mold structure utilized for obtaining a compacted soil specimen;

FIG. 2 is a perspective view illustrating the separation of the upper and lower mold parts;

FIG. 3 is a side elevation of the soil pulverizing device of the invention;

FIG. 4 is a plan view of the soil pulverizing device;

FIG. 5 is an enlarged fragmentary sectional view illustrating the cutting action achieved with the soil pulverizing device;

FIG. 6 is a cross-sectional view taken about the line 6-6 ofFlG. 6; and,

FIG. 7 is a perspective view of the blade utilized in the device of the invention.

This invention is generally directed to a soil pulverizing device to be utilized in a compaction testing operation. The device is particularly adapted to reduce a compacted soil specimen to a fine state whereby the moisture content of .the soil can be changed so that a succeeding test can be conducted on the same soil tov determine the density variation which occurs as a result of the moisture variation.

The device of the invention particularly comprises a base for supporting a mold containing a compacted soil specimen. Separate means are provided for supporting a pulverizing blade whereby the. blade can be positioned adjacent the mold. Means are provided for driving the blade whereby the blade rotates relative to the mold. The drive means also operates to simultaneously advance the rotating blade inwardly of the mold for engagement with the compacted specimen whereby the cutting edge of the blade serves to reduce the compacted specimen to a fine state via a simultaneous raking and scraping of the exposed face of the coil specimen.

ln the drawings, FlGS. l and 2 illustrate a mold assembly 10 comprising a collar or upper mold l2 and the compaction or lower mold 14. The lower mold is mounted on a base 16 by means of two slotted lugs 15 on the sides of each mold positioned apart. These lugs receive threaded rods 17 and they are secured by means of wing nuts 19. A reduced diameter rim 21 is defined by the lower mold l4, and the upper mold defines a rim portion 23 to provide for interfitting of these molds. The assembly is adapted to receive an amount of soil 18, that is, the soil to be compacted.

A suitable compacting means such as a ram is employed for producing a compacted specimen within the mold. The energy applied by the ram is controlled so that the soil will be subjected to the same compacting energy in successive stages of the compaction test operation.

After obtaining compacted material in the mold, the collar (or upper mold) 12 is separated from the lower mold 14 by twisting and lifting the collar vertically relative to the lower mold. Care is exercised that this oper- 3 ation does not.remove soil below the edge of the lower mold. The exposed soil protruding above the top edge of the lower mold 14 is struck off'flush withthe mold edge using a metal straight. edge or-other scraping-device. The mold 14 is then disengaged from the base plate l6an'dweighed so the density for that soil specimen may be determined.

FIGS. 3 throng-b6 illustrate an example of a soil pulverizing device 22 characterized by the features of the invention. This device includes a channel shaped base '24 having wall 26 to which a first block 28 is secured by means of bolts 30. An upstanding base member 32 is welded to this block to provide a means of attaching the soil mold into the system and to further provide a resistance on the confined end of the soil sample so that the sample can be reduced at the free end. Additional blocks 34 and 36 are secured to the base 24 by means of bolts 38 and 40, respectively. Vertically extending plate members 42 and 44 are welded to these blocks.

The base member 32 defines a seat 46 dimensioned to receive the bottom mold 14. As shown in FIG. 5, the mold bottom 47 includes a reduced diameter section 49 which insures centering within the seat 46. A pair of threaded pins 48 are fixed at two corners of the base member, and these pins extend outwardly in straddling relationship relative to a bottom mold 14 when the mold is positioned on the base to align the bottom mold using the two slotted lugs on the mold sides and wing nuts 52.

FIG. 5 illustrates a compaction mold 14 in position on the base 32. The mold is inserted and the mold lug notches are positioned on the receiving pins 48. The wing nuts 52 are tightened whereby the compaction mold is rigidly fixed in position on the base. Alternatively, for softer soil, the operator positions the mold on pins 48 and holds the mold with one hand, using the other to rotate the screw crank 68.

The plate member 42 defines a bore 54 and an internally threaded nut 56 is welded to this plate member with the threaded opening 58 of the nut being aligned with the bore 54. The plate member 44 defines a bore 60 containing a bushing which is also aligned with the bore 54. A shaft 62 defines a threaded portion 64 and an unthreaded section 66. The section 66 is receivable within the bore 60 while the threaded portion 64 passes through bore 54 and into engagement with the threaded opening 58 of the nut 56.

An operating handle 68 is secured at the end of the unthreaded shaft portion 66 whereby the shaft is rotatable relative to the plates 42 and 44. A nut 70 is welded onto the end of the threaded portion 64, and a blade 72 is welded to this nut. Accordingly, the blade 72 will rotate upon rotation of the shaft 62.

As best illustrated in FIG. 7, the blade 72 defines a serrated edge portion 74 and a straight edge portion 76, these portions each occupying approximately one-half of the length of the blade. The straight edge portion 76 is bent-over to define a scraping edge and a scoop or auger configuration.

In the use of the construction of this invention, a compacted specimen is first formed in the mold as shown in FIG. I. In order to insure the use of a specimen of a known volume, the upper mold or collar 12 portion is used during compaction, and then is separated from the lower mold portion 14. The soil surface of the specimen 18 in the lower mold portion protruding above the top edge of the mold is removed with any suitable tool. When the lower mold is thus prepared (and after a density determination is made), the mold is clamped or placed in position on the soil pulverizing device as shown in FIG. 5.

The mounting of the blade 72 on the threaded shaft portion 64 enables use of the blade for accomplishing the desired soil pulverizing. Thus, when rotating the shaft by means of the handle 68, the blade 72 can be moved forwardly into engagement with the exposed surface of the compacted specimen. By providing the threaded engagement of the shaft with nut 56, the axial movement of the blade proceeds at a controlled rate depending upon the speed of shaft rotation.

The blade configuration accomplishes break-up of the compacted material due to the serrated edge portion 74 which acts as a rake or scratching device. This loosens the soil and displaces small gravel which may be present. Simultaneously the other half of the blade being straight-edged and slightly curved scrapes this loosened soil, removing it from the face of the sample. The screw 62 has a pitch selected to control the thicknessof soil being scraped so that the resulting pulverized soil is reduced to the proper sieve size. A one-inch diameter rod with 14 threads per inch is typical. Any suitable means can be used to collect the pulverized soil from the mold.

The construction described provides many distinct advantages when compared with prior art structures. The fact that a mechanized blade is employed for contact with the soil particle largely eliminates any inconsistencies in the soil pulverized. Thus, the working edge of the blade presents a uniform pulverizing action contrary to the non-uniform action which is inherently involved where manually operated tools such as spatulas are used for reducing a compacted specimen to a pulverized state.

Due to the operating uniformity, the test results which are obtained tend to be more consistent and thus more reliable. In this connection, the soil which results after pulverizing a specimen tends to accept water for increasing the moisture content in a highly uniform fashion. Since the compaction test requires a series of compacted specimens, each of which must be pulverized, followed by the addition of water, this becomes a highly significant factor.

The structure of the invention greatly reduces the time and effort required for obtaining a pulverized sample. The strain of scraping away material from a highly compacted specimen is eliminated since the operation of handle 68 requires much less effort. In addition, the invention proves to be a considerable time saver when compared with techniques used by the prior art. Whereas the conventional scraping methods may take a matter of hours, the use of the soil pulverizing means of this invention involves 1 minute or less. As much as 2 hours time for a single compaction test can be saved when using a soil pulverizing device of this invention. The advantageous results are achieved with a manually operated unit of the type illustrated; however, similar results can be achieved if a motor drive were provided for the shaft 62.

As is revealed in the drawings, the structure of the invention is quite straightforward in design so that significant expense is not involved in the production of devices of this type. Similarly, the movable parts employed are extremely basic in nature so that maintenance costs will not be significant. The'construction,

therefore, provides an ext-remely efficient means for obtaining the pulverized'soil while also-insuring that the compaction testing resultswill not be unreliable due to inconsistencies in the reduction techniques employed. The blade may be produced from any suitable material, for example, a tool steel. The dimensions of the structure are controlled by the testing standards applicable. [n a typical case, the blade will be 3% inch long to accommodate a 4 inch l.D. mold, with 87/32 inch teeth being provided on the blade.

It will be understood that various changes and modifications may be made in the above described construction which provide the characteristics of the invention without departing from the spirit thereof particularly as defined in the following claims.

That which is claimed is:

1. In a compaction testing system wherein a compacted soil specimen is obtained in a mold and then pulverized to a fine state, the improvement in a soil pulverizing device comprising:

a base for mounting said mold;

means defined by the mold and complementary means defined by the base for securing the mold in position when the mold is mounted on the base;

a pulverizing blade having a serrated edge portion for contact with said specimen wherein said portion extends for approximately half the length of the blade and wherein the remaining half of the blade edge is bent inwardly to provide both a scraper to remove the loosened soil from the sample face and as an auger whereby material engaged by said blade is driven outwardly of the mold;

means for supporting said blade to accurately align the blade relative to a mold mounted on said base and to position the blade adjacent the mold; and

means for driving said blade whereby the blade rotates relative to the mold, said means supporting the blade including means for simultaneously moving the blade inwardly of the mold for engaging the material therein as the blade rotates whereby the rotation and inward movement of the blade gradually pulverizes the compacted specimen to a fine state.

2. A device in accordance with claim 1 including a threaded shaft and means securing said blade at one end of said shaft, a threaded support for said shaft, and means for rotating said shaft whereby the shaft and blade move relative to said threaded support.

3. A device in accordance with claim 2 including a frame, and means mounting said base and said threaded support on said frame whereby rotation of said shaft moves the shaft and blade relative to said base;

4. A device in accordance with claim 3 including means for removably clamping a mold on said base, said frame being horizontally positioned and said base extending vertically upwardly relative to the frame, the axis of said shaft extending parallel to said frame and perpendicular to said base.

5. A device in accordance with claim 1 wherein said compacted specimen initially defines an outer surface which lies in substantially the same plane as the outer edge of said mold and is substantially flush with said outer edge, said blade defining a cutting edge which is maintained substantially parallel with said outer surface and wherein said blade has a length substantially equal to the inner diameter of said mold whereby said specimen is gradually pulverized completely across the mold as the blade rotates and moves inwardly with the continuously exposed unpulverized surface of the specimen remaining substantially parallel with said cutting edge. 

1. In a compaction testing system wherein a compacted soil specimen is obtained in a mold and then pulverized to a fine state, the improvement in a soil pulverizing device comprising: a base for mounting said mold; means defined by the mold and complementary means defined by the base for securing the mold in position when the mold is mounted on the base; a pulverizing blade having a serrated edge portion for contact with said specimen wherein said portion extends for approximately half the length of the blade and wherein the remaining half of the blade edge is bent inwardly to provide both a scraper to remove the loosened soil from the sample face and as an auger whereby material engaged by said blade is driven outwardly of the mold; means for supporting said blade to accurately align the blade relative to a mold mounted on said base and to position the blade adjacent the mold; and means for driving said blade whereby the blade rotates relative to the mold, said means supporting the blade including means for simultaneously moving the blade inwardly of the mold for engaging the material therein as the blade rotates whereby the rotation and inward movement of the blade gradually pulverizes the compacted specimen to a fine state.
 2. A device in accordance with claim 1 including a threaded shaft and means securing said blade at one end of said shaft, a threaded support for said shaft, and means for rotating said shaft whereby the shaft and blade move relative to said threaded support.
 3. A device in accordance with claim 2 including a frame, and means mounting said base and said threaded support on said frame whereby rotation of said shaft moves the shaft and blade relative to said base.
 4. A device in accordance with claim 3 including means for removably clamping a mold on said base, said frame being horizontally positioned and said base extending vertically upwardly relative to the frame, the axis of said shaft extending parallel to said frame and perpendicular to said base.
 5. A device in accordance with claim 1 wherein said compacted specimen initially defines an outer surface which lies in substantially the same plane as the outer edge of said mold and is substantially flush with said outer edge, said blade defining a cutting edge which is maintained substantially parallel with said outer surface and wherein said blade has a length substantially equal to the inner diameter of said mold whereby said specimen is gradually pulverized completely across the mold as the blade rotates and moves inwardly with the continuously exposed unpulverized surface of the specimen remaining substantially parallel with said cutting edge. 